A temperature sensing cable alarm testing method and device based on the Internet of Things

Abstract

The invention discloses a temperature-sensing cable alarm test method and device based on the Internet of Things, and relates to the technical field of temperature-sensing cable monitoring. The invention constructs voltage, current, and frequency fluctuation models based on real-time temperature data to simulate high-voltage impact scenarios, effectively identify temperature over-limit and response lag situations, and monitors temperature changes through real-time slopes, so as to respond to abnormal situations in a timely manner, greatly improve the detection sensitivity of cables in different environments, reduce the false alarm rate, introduce a transient power model, accurately calculate the transient power and temperature change rate of the cable during high-voltage impact, improve the response speed under extreme conditions, and quickly identify whether the cable responds within a specified time, significantly improve the safety in emergencies, analyze the frequency components of the temperature signal through Fourier transform, effectively distinguish transient high-frequency false alarms from low-frequency real fire signals, greatly reduce the false alarm frequency of the system, and enhance the reliability of the overall device.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature-sensing cable monitoring, and in particular to a temperature-sensing cable alarm testing method and device based on the Internet of Things. Background Art

[0002] In fire alarm systems, temperature sensing cables are widely used to monitor changes in ambient temperature and trigger alarm signals. However, in actual applications, temperature sensing cables not only have to work under constant or slowly changing temperatures, but also need to cope with dynamic loads and high voltage shocks.

[0003] Dynamic load refers to the situation where voltage and current change frequently during the operation of the power system or equipment. In this environment, the temperature sensing cable is easily affected by electromagnetic interference, overload and transient fluctuations, resulting in unstable working state. This phenomenon is particularly obvious in large industrial sites, natural gas stations, near power equipment, etc. High-voltage shock is a current overload caused by sudden high voltage or lightning strikes in the power grid. This shock may instantly damage the temperature sensing cable or degrade its performance.

[0004] In fire alarm systems, temperature sensing cables must maintain high sensitivity under these extreme power conditions to ensure that the system can respond to fire risks in a timely manner. However, traditional temperature sensing cable testing methods are mainly focused on standard temperature conditions. When facing dynamic loads and high-voltage shocks, traditional temperature sensing cables are mostly wrapped with electromagnetic shielding materials to reduce external electromagnetic interference. Although this method can partially alleviate interference, the shielding effect is limited under high-intensity dynamic power changes.

[0005] To cope with high-voltage shocks, some solutions will add overvoltage protection devices to the cable system to prevent the temperature-sensing cable from being damaged. However, the overvoltage protection device can only work within the set threshold range. For higher intensity or sudden shocks, the temperature-sensing cable may still be damaged. When the temperature-sensing cable has an abnormal alarm under dynamic load or high-voltage environment, manual detection and troubleshooting are required, which is time-consuming and inefficient, and is prone to missed alarms and false alarms. Therefore, a temperature-sensing cable alarm testing method and device based on the Internet of Things is urgently needed to solve such problems. Summary of the invention

[0006] In view of the above existing problems, the present invention is proposed.

[0007] The present invention provides a temperature-sensing cable alarm testing method and device based on the Internet of Things to solve the problem that the traditional temperature-sensing cable testing method has great limitations when dealing with dynamic loads and high-voltage impact power environments, cannot monitor and respond to transient power fluctuations in real time, and lacks comprehensive testing capabilities for sudden high voltages.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] On the one hand, the present invention provides a temperature-sensitive cable alarm test device based on the Internet of Things, which includes:

[0010] The temperature sensing cable node data acquisition module is used to collect the temperature data of each node of the temperature sensing cable and transmit the data to the remote server.

[0011] Temperature sensors are placed at the temperature-sensing cable nodes to monitor temperature changes in real time, and the NBIoT wireless network is used to transmit the temperature data of the nodes to the remote server.

[0012] Remote servers, including:

[0013] Dynamic load and grid fluctuation test module, used to evaluate the performance of temperature sensing cables under grid fluctuations and load changes, detect potential anomalies and response problems,

[0014] High voltage impact and transient response test module, used to test the transient response capability of temperature sensing cables under sudden high voltage or lightning conditions, detect their anti-interference ability and alarm accuracy,

[0015] Multi-node response uniformity test module, used to verify the uniformity of multi-point arrangement,

[0016] The report generation module analyzes the data generated by each test module and outputs an overall performance report.

[0017] On the other hand, the present invention provides a temperature sensing cable alarm testing method based on the Internet of Things, comprising:

[0018] Step S1, temperature sensing cable data collection,

[0019] The temperature sensors deployed on the temperature-sensing cable nodes collect the node temperature data in real time and transmit the temperature data to the remote server using the NBIoT wireless network.

[0020] Step S2, dynamic load test,

[0021] The remote server performs dynamic load testing based on the temperature data in S1, simulating fluctuations and load changes in the power grid, adjusting voltage, current and frequency parameters while monitoring temperature changes under different load conditions, marking abnormal data and issuing alarms.

[0022] Step S3, high voltage shock test,

[0023] Based on the temperature data in S1, the remote server simulates sudden high voltage or lightning strike scenarios, performs high voltage impact tests, and tests the transient response capability of the cable.

[0024] Step S4, response uniformity test,

[0025] Based on the dynamic load test data and high-voltage impact data in S2 and S3, the transient false alarms and real fire signals are distinguished, the alarm responses at different locations are analyzed, and the response of the cable at different locations is tested to see whether it is uniform. When an abnormality is detected, a local alarm is issued.

[0026] Step S5, comprehensive data analysis,

[0027] The data output from step S1 to step S4 are analyzed, including normal working conditions, dynamic loads, high-voltage shocks, and multi-point response performances, and data comparisons under different conditions are performed to generate a test report.

[0028] Furthermore, the abnormal data marked in step S2 include temperature exceeding the limit and response lag.

[0029] Furthermore, in step S2, the dynamic load test is performed as follows:

[0030] Construct a dynamic model of voltage, current, and frequency. Assume that the voltage at a certain moment is , the current is , the frequency is And they are all time functions, then their volatility is expressed as:

[0031] ,in, It's time The voltage value at the moment, is the reference voltage, is the coefficient of voltage fluctuation amplitude, is the basic frequency of the power grid,

[0032] Current and frequency The fluctuation expression of is:

[0033] ,

[0034] ,in, It's time The current value at the moment, is the reference current is the coefficient of the current fluctuation amplitude, is the phase difference of the current fluctuations, It's time The frequency value at the moment, is the standard frequency of the power grid, is the coefficient of the frequency fluctuation amplitude,

[0035] temperature Will be affected by voltage , Current , and the frequency The power equation is used here to associate the parameters. It is expressed as:

[0036] , temperature changes It is expressed by the heat conduction equation:

[0037] ,in, It's time The temperature of the moment, is the initial temperature, is the thermal resistance of the cable, is the thermal capacity of the cable, is the thermal time constant.

[0038] Furthermore, in step S2, the method of performing the dynamic load test also includes:

[0039] To perform temperature over-limit detection:

[0040] When the temperature Exceeding the set threshold When the alarm is triggered,

[0041] To perform response hysteresis detection:

[0042] Real-time monitoring of the slope of temperature change , detect whether the temperature responds too slowly after the load changes. If the temperature response lag time Exceeding critical value , it is marked as delayed response and an alarm is issued:

[0043] ,like , then an alarm is triggered, where is the upper temperature limit, is the maximum allowable lag time of the temperature response,

[0044] At every point in time Based on the monitored temperature data , compared with the set threshold And the hysteresis of the detection temperature response , determine whether to trigger an abnormal alarm.

[0045] Furthermore, in step S3, the high voltage shock test method is:

[0046] Simulate sudden high voltage shock scenario:

[0047] ,in, Indicates time The transient impulse voltage that the cable is subjected to at any moment, Indicates the steady-state voltage value, that is, the voltage value of the cable under normal operation. Indicates the ratio of high-voltage shock amplitude, that is, the intensity of transient shock. It represents the shock wave attenuation coefficient, controls the attenuation speed of transient shock, and simulates the natural decay process after voltage shock. Represents the angular frequency of the impact event, used to describe the high-frequency electromagnetic interference effect, represents the time variable, i.e. the time when the shock occurs,

[0048] Simulate the transient change of current:

[0049] ,in, Indicates time The instantaneous current value of the cable at the moment, Indicates the steady-state current value, that is, the current of the cable under normal operation. represents the phase shift of the current,

[0050] Perform transient power calculations and thermal effect simulations:

[0051] ,in, Indicates time The transient power value at the moment, that is, the power consumed by the cable when it is subjected to high voltage shock. and Represents the values ​​of transient voltage and current respectively. This power This will cause the cable temperature to rise, and the temperature response can be expressed as:

[0052] ,in, Indicates time The cable temperature at the time, Indicates the initial temperature or ambient temperature, that is, the temperature of the cable before the impact, Indicates the thermal resistance of the cable, that is, the ability of the cable to resist temperature changes. represents the instantaneous power, Indicates the thermal capacity of the cable, that is, the ability of the cable to store heat. Represents the thermal time constant, that is, the temperature response speed.

[0053] Furthermore, in step S3, the high voltage shock test method further includes:

[0054] Perform transient response capability test and calculate the temperature change rate:

[0055] ,in, Indicates the rate of change of temperature over time, compared to the rate of change of temperature and preset response thresholds , to determine whether the cable responds fast enough. If the temperature change rate is lower than the threshold, it means that the cable fails to respond to the sudden high-voltage shock in time, and an alarm is triggered.

[0056] There are two types of abnormal conditions in cables during sudden high voltage shocks:

[0057] Temperature Exceeds Limit: If the temperature Exceeding the preset safety threshold , then alarm,

[0058] Response hysteresis: The hysteresis of the detection temperature change rate. If the response time Exceeding the set allowed time , then alarm, Indicates the response time of the cable from high voltage shock to significant temperature change. Indicates the maximum allowed response time.

[0059] Furthermore, in step S4, the response uniformity test method is:

[0060] Analyzing the temperature signal in the frequency domain, the real fire signal is characterized by a continuous temperature rise with a low frequency, while the transient false alarm signal is a high-frequency short-term fluctuation. Here, Fourier transform FFT is used to convert the temperature signal from the time domain to the frequency domain for spectrum analysis:

[0061] ,in, Indicates temperature signal Represented in the frequency domain, Indicates time The temperature signal at the moment, represents the frequency component, that is, the frequency of the signal, represents the imaginary unit, that is, the transformation of complex space,

[0062] Analyze the spectrum obtained after Fourier transform , detect the frequency components of the signal. If there is an obvious energy peak in the high frequency band, it is judged as a transient false alarm. If the low frequency component gradually increases, it is judged as a real fire signal.

[0063] False alarm judgment criteria: Setting frequency threshold , when the frequency If the energy If it is higher than the set value, it is considered as a transient false alarm. ,and It is considered a false alarm. represents the frequency domain energy threshold,

[0064] True fire judgment criteria: On the contrary, if the signal energy is concentrated in the low frequency band , and the duration is long, it is defined as a real fire signal. ,and , it is regarded as a real fire signal. Indicates the low frequency energy threshold of the fire signal.

[0065] Furthermore, in step S4, the response uniformity test method further includes:

[0066] The temperature response of multiple nodes is analyzed. Temperature sensors are arranged at different locations to record the temperature signal of each node ,in , calculate the deviation of each node from the mean temperature:

[0067] ,in, Representation Node The deviation from the mean temperature, Representation Node The temperature, represents the average temperature of all nodes,

[0068] Calculate the temperature standard deviation of all nodes. The larger the standard deviation, the more uneven the response:

[0069] ,in, Indicates time The standard deviation of the temperature response at time,

[0070] When the standard deviation Exceeds the set uniformity threshold When the cable is not responding uniformly, a local alarm is sounded: , a local alarm is issued, represents the uniformity threshold, i.e. the maximum allowed temperature response deviation,

[0071] The temperature response of each node , set the allowed response range , when the node temperature When the range is exceeded, a local abnormal alarm is triggered: ,

[0072] or , then a local abnormal alarm is triggered. and Indicates the preset upper and lower temperature limits.

[0073] Combine the abnormal signals of multiple nodes to detect whether the nodes in a certain area are abnormal at the same time and issue a regional alarm. adjacent nodes, if more than If all nodes exceed the limit at the same time, a regional alarm will be issued: , a regional alert is issued. is the indicator function, when If true, the value is 1, otherwise it is 0. It is the node number threshold that triggers the regional alarm.

[0074] Furthermore, in step S5, the comprehensive data analysis method is:

[0075] Normalize the data:

[0076] ,in Representation Node In time The normalized temperature at time, Representation Node In time The original temperature data at the time, and Representation Node The temperature data of all nodes are normalized to the minimum and maximum temperature values ​​during the test. interval,

[0077] Under normal working conditions, the temperature of the cable remains stable, and the temperature difference between each node is not large. Calculate the average temperature under normal working conditions and standard deviation :

[0078] ,in, Indicates time The mean temperature of all nodes at the moment, Represents the total number of nodes,

[0079] ,in, Indicates time The temperature standard deviation at the moment measures the dispersion of the temperature of each node. Exceeding the set normal operating threshold When , an alarm signal is issued, marking the time period as abnormal: , then an alarm is issued, Indicates the maximum standard deviation allowed for temperature response under normal operating conditions.

[0080] Under dynamic load conditions, calculate the slope of the temperature under load conditions , evaluate the cable's ability to respond to load fluctuations:

[0081] ,in, Representation Node In time The rate of change of temperature at a moment, that is, the temperature response speed caused by load fluctuations, Represents the time interval used to calculate the temperature change rate, perform mean and standard deviation analysis on the temperature change rate of all nodes, and evaluate the performance of the cable under dynamic load: ,in, Indicates time The average temperature change rate of all nodes at the moment is used to evaluate the overall response speed of the cable.

[0082] ,in, Indicates time The standard deviation of the temperature change rate at each moment,

[0083] When the standard deviation Exceeding the set threshold When the alarm is sounded: , an alarm is sounded, Indicates the maximum standard deviation allowed for the temperature response change rate under dynamic load.

[0084] Detect the transient response time of each node , that is, the time required for the cable temperature to reach a certain set value after the impact occurs. The transient response time is calculated as:

[0085] ,in, Representation Node The transient response time, that is, the temperature first reaches The moment of time, Indicates the set temperature threshold, marking whether the cable successfully responds to the high voltage shock.

[0086] Calculate the mean and standard deviation of the transient response time of each node:

[0087] ,in, represents the average transient response time of all nodes,

[0088] ,in, Represents the standard deviation of transient response time, which measures the discreteness of each node’s response time.

[0089] when Exceeding the set threshold When an abnormal response alarm is issued: , an abnormal response alarm is issued. represents the maximum allowable standard deviation of the transient response time,

[0090] Perform a global analysis of the temperature response of each node, calculate the mean and standard deviation of the node under all working conditions, and summarize the temperature data under normal working conditions, dynamic loads, and high-pressure shock conditions:

[0091] ,in, represents the average temperature of all nodes in all time periods, Represents the total number of time periods, that is, the total time under all test conditions.

[0092] The beneficial effects of the present invention are:

[0093] The present invention deploys temperature sensors at multiple nodes of the temperature-sensing cable and uses the NBIoT network for real-time data transmission, thereby improving data accuracy. Voltage, current, and frequency fluctuation models are constructed based on the collected real-time data to simulate high-voltage impact scenarios, accurately identify temperature over-limit and response lag situations, and monitor temperature changes through real-time slope. It can respond to abnormal situations in a timely manner, greatly improving the detection sensitivity of the cable in different environments and reducing the false alarm rate.

[0094] The present invention introduces a transient power model, which can accurately calculate the transient power and temperature change rate of the cable when a high voltage shock occurs, thereby improving the response speed under extreme conditions and quickly identifying whether the cable responds within a specified time, thereby significantly improving safety in emergencies.

[0095] The present invention analyzes the frequency components of the temperature signal through Fourier transform, effectively distinguishes transient high-frequency false alarms from low-frequency real fire signals, greatly reduces the false alarm frequency of the system, and enhances the reliability of the overall device.

[0096] The present invention performs uniformity analysis on the temperature responses of multiple nodes, calculates the response differences and standard deviations between nodes, and maintains alarm consistency for cables at all locations. When the responses of certain nodes are abnormal, local or regional alarms can be issued, thus solving the problem of uneven response in traditional testing methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0097] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0098] Figure 1It is a structural schematic diagram of a temperature-sensing cable alarm test device based on the Internet of Things of the present invention;

[0099] Figure 2 It is a schematic flow chart of the temperature-sensing cable alarm testing method based on the Internet of Things of the present invention. DETAILED DESCRIPTION

[0100] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0101] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0102] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0103] Example 1, reference Figure 1 , this embodiment provides a temperature-sensitive cable alarm test device based on the Internet of Things, including:

[0104] The temperature sensing cable node data acquisition module is used to collect the temperature data of each node of the temperature sensing cable and transmit the data to the remote server.

[0105] Temperature sensors are placed at the temperature-sensing cable nodes to monitor temperature changes in real time, and the NBIoT wireless network is used to transmit the temperature data of the nodes to the remote server.

[0106] Remote servers, including:

[0107] Dynamic load and grid fluctuation test module, used to evaluate the performance of temperature sensing cables under grid fluctuations and load changes, detect potential anomalies and response problems,

[0108] High voltage impact and transient response test module, used to test the transient response capability of temperature sensing cables under sudden high voltage or lightning conditions, detect their anti-interference ability and alarm accuracy,

[0109] Multi-node response uniformity test module, used to verify the uniformity of multi-point arrangement,

[0110] The report generation module analyzes the data generated by each test module and outputs an overall performance report.

[0111] Example 2, reference Figure 2 , this embodiment provides a temperature-sensitive cable alarm testing method based on the Internet of Things, comprising the following steps:

[0112] Step S1, temperature sensing cable data collection,

[0113] The temperature sensors deployed on the temperature-sensing cable nodes collect the node temperature data in real time and transmit the temperature data to the remote server using the NBIoT wireless network.

[0114] Specifically, temperature sensors are deployed at the temperature-sensing cable nodes and the NBIoT network is used for real-time data collection. Normalization processing is used to avoid data deviation problems under different test conditions, so that the test device can compare and analyze multiple situations under the same standards to ensure test accuracy.

[0115] Step S2, dynamic load test,

[0116] The remote server performs dynamic load testing based on the temperature data in S1, simulating fluctuations and load changes in the power grid, adjusting voltage, current and frequency parameters while monitoring temperature changes under different load conditions, marking abnormal data and issuing alarms.

[0117] The abnormal data marked in step S2 include temperature exceeding the limit and response hysteresis;

[0118] In step S2, the dynamic load test is performed as follows:

[0119] Construct a dynamic model of voltage, current, and frequency. Assume that the voltage at a certain moment is , the current is , the frequency is And they are all time functions, then their volatility is expressed as:

[0120] ,in, It's time The voltage value at the moment, is the reference voltage, is the coefficient of voltage fluctuation amplitude, is the basic frequency of the power grid,

[0121] Current and frequency The fluctuation expression of is:

[0122] ,

[0123] ,in, It's time The current value at the moment, is the reference current is the coefficient of the current fluctuation amplitude, is the phase difference of the current fluctuations, It's time The frequency value at the moment, is the standard frequency of the power grid, is the coefficient of the frequency fluctuation amplitude,

[0124] temperature Will be affected by voltage , Current , and the frequency The power equation is used here to associate the parameters. It is expressed as:

[0125] , temperature changes It is expressed by the heat conduction equation:

[0126] ,in, It's time The temperature of the moment, is the initial temperature, is the thermal resistance of the cable, is the thermal capacity of the cable, is the thermal time constant.

[0127] In step S2, the method of performing the dynamic load test also includes:

[0128] To perform temperature over-limit detection:

[0129] When the temperature Exceeding the set threshold When the alarm is triggered,

[0130] To perform response hysteresis detection:

[0131] Real-time monitoring of the slope of temperature change , detect whether the temperature responds too slowly after the load changes. If the temperature response lag time Exceeding critical value , it is marked as response lag and an alarm is issued:

[0132] ,like , then an alarm is triggered, where is the upper temperature limit, is the maximum allowable lag time of the temperature response,

[0133] At every point in time Based on the monitored temperature data , compared with the set threshold And the hysteresis of the detection temperature response , determine whether to trigger an abnormal alarm.

[0134] Specifically, a fluctuation model of voltage, current and frequency is constructed in the dynamic load test to reflect the operation of the cable in the real power grid. By detecting the temperature response of the dynamic load, the temperature over-limit and response lag are identified. By real-time monitoring of the temperature change slope, the cable's reaction speed to load fluctuations can be effectively judged. The response lag can be quickly identified and an alarm can be triggered.

[0135] Step S3, high voltage shock test,

[0136] Based on the temperature data in S1, the remote server simulates sudden high voltage or lightning strike scenarios, performs high voltage impact tests, and tests the transient response capability of the cable.

[0137] In step S3, the high voltage shock test method is:

[0138] Simulate sudden high voltage shock scenario:

[0139] ,in, Indicates time The transient impulse voltage that the cable is subjected to at any moment, Indicates the steady-state voltage value, that is, the voltage value of the cable under normal operation. Indicates the ratio of high-voltage shock amplitude, that is, the intensity of transient shock. It represents the shock wave attenuation coefficient, controls the attenuation speed of transient shock, and simulates the natural decay process after voltage shock. Represents the angular frequency of the impact event, used to describe the high-frequency electromagnetic interference effect, represents the time variable, i.e. the time when the shock occurs,

[0140] Simulate the transient change of current:

[0141] ,in, Indicates time The instantaneous current value of the cable at the moment, Indicates the steady-state current value, that is, the current of the cable under normal operation. represents the phase shift of the current,

[0142] Perform transient power calculations and thermal effect simulations:

[0143] ,in, Indicates time The transient power value at the moment, that is, the power consumed by the cable when it is subjected to high voltage shock. and Represents the values ​​of transient voltage and current respectively. This power This will cause the cable temperature to rise, and the temperature response can be expressed as:

[0144] ,in, Indicates time The cable temperature at the time, Indicates the initial temperature or ambient temperature, that is, the temperature of the cable before the impact, Indicates the thermal resistance of the cable, that is, the ability of the cable to resist temperature changes. represents the instantaneous power, Indicates the thermal capacity of the cable, that is, the ability of the cable to store heat. Represents the thermal time constant, that is, the temperature response speed.

[0145] In step S3, the high voltage shock test method further includes:

[0146] Perform transient response capability test and calculate the temperature change rate:

[0147] ,in, Indicates the rate of change of temperature over time, compared to the rate of change of temperature and preset response thresholds , to determine whether the cable responds fast enough. If the temperature change rate is lower than the threshold, it means that the cable fails to respond to the sudden high-voltage shock in time, and an alarm is triggered.

[0148] There are two types of abnormal conditions in cables during sudden high voltage shocks:

[0149] Temperature Exceeds Limit: If the temperature Exceeding the preset safety threshold , then alarm,

[0150] Response hysteresis: The hysteresis of the detection temperature change rate. If the response time Exceeding the set allowed time , then alarm, Indicates the response time of the cable from high voltage shock to significant temperature change. Indicates the maximum allowed response time.

[0151] Specifically, for the test of high-voltage shock, the transient response of the cable during high-voltage shock is simulated by modeling the sudden transient changes of voltage and current, combining the transient power equation and the heat conduction equation, effectively testing the transient response capability of the cable, and through the analysis of the temperature change rate, timely judging whether the cable responds insufficiently or exceeds the temperature limit under extreme conditions. In addition, the detection mechanism based on transient response can quickly capture abnormal conditions of temperature exceeding the limit and response delay.

[0152] Step S4, response uniformity test,

[0153] Based on the dynamic load test data and high-voltage impact data in S2 and S3, the transient false alarms and real fire signals are distinguished, the alarm responses at different locations are analyzed, and the response of the cable at different locations is tested to see whether it is uniform. When an abnormality is detected, a local alarm is issued.

[0154] In step S4, the response uniformity test method is:

[0155] Analyzing the temperature signal in the frequency domain, the real fire signal is characterized by a continuous temperature rise with a low frequency, while the transient false alarm signal is a high-frequency short-term fluctuation. Here, Fourier transform FFT is used to convert the temperature signal from the time domain to the frequency domain for spectrum analysis:

[0156] ,in, Indicates temperature signal Represented in the frequency domain, Indicates time The temperature signal at the moment, represents the frequency component, that is, the frequency of the signal, represents the imaginary unit, that is, the transformation of complex space,

[0157] Analyze the spectrum obtained after Fourier transform , detect the frequency components of the signal. If there is an obvious energy peak in the high frequency band, it is judged as a transient false alarm. If the low frequency component gradually increases, it is judged as a real fire signal.

[0158] False alarm judgment criteria: Setting frequency threshold , when the frequency If the energy If it is higher than the set value, it is considered as a transient false alarm. ,and It is considered a false alarm. represents the frequency domain energy threshold,

[0159] True fire judgment criteria: On the contrary, if the signal energy is concentrated in the low frequency band , and the duration is long, it is defined as a real fire signal. ,and , it is regarded as a real fire signal. Indicates the low frequency energy threshold of the fire signal.

[0160] In step S4, the response uniformity test method further includes:

[0161] The temperature response of multiple nodes is analyzed. Temperature sensors are arranged at different locations to record the temperature signal of each node ,in , calculate the deviation of each node from the mean temperature:

[0162] ,in, Representation Node The deviation from the mean temperature, Representation Node The temperature, represents the average temperature of all nodes,

[0163] Calculate the temperature standard deviation of all nodes. The larger the standard deviation, the more uneven the response:

[0164] ,in, Indicates time The standard deviation of the temperature response at time,

[0165] When the standard deviation Exceeds the set uniformity threshold When the cable is not responding uniformly, a local alarm is sounded: , a local alarm is issued, represents the uniformity threshold, i.e. the maximum allowed temperature response deviation,

[0166] The temperature response of each node , set the allowed response range , when the node temperature When the range is exceeded, a local abnormal alarm is triggered: ,

[0167] or , then a local abnormal alarm is triggered. and Indicates the preset upper and lower temperature limits.

[0168] Combine the abnormal signals of multiple nodes to detect whether the nodes in a certain area are abnormal at the same time and issue a regional alarm. adjacent nodes, if more than If all nodes exceed the limit at the same time, a regional alarm will be issued: , a regional alert is issued. is the indicator function, when If true, the value is 1, otherwise it is 0. It is the node number threshold that triggers the regional alarm.

[0169] Specifically, in the response uniformity test, Fourier transform is used to convert the temperature signal from the time domain to the frequency domain for analysis, so as to distinguish transient false alarms from real fire signals. It can quickly identify high-frequency false alarms and low-frequency real fire signals, effectively improving the system's false alarm recognition ability. In addition, through the response uniformity detection and standard deviation analysis of each node, it can accurately determine whether the response of the cable at different positions is uniform, so as to maintain the consistency and accuracy of the overall alarm.

[0170] Step S5, comprehensive data analysis,

[0171] Analyze the data output from step S1 to step S4, including normal working conditions, dynamic load, high voltage shock and multi-point response performance, compare the data under different conditions, and generate a test report;

[0172] In step S5, the comprehensive data analysis method is:

[0173] Normalize the data:

[0174] ,in Representation Node In time The normalized temperature at time, Representation Node In time The original temperature data at the time, and Representation Node The temperature data of all nodes are normalized to the minimum and maximum temperature values ​​during the test. interval,

[0175] Under normal working conditions, the temperature of the cable remains stable, and the temperature difference between each node is not large. Calculate the average temperature under normal working conditions and standard deviation :

[0176] ,in, Indicates time The mean temperature of all nodes at the moment, Represents the total number of nodes,

[0177] ,in, Indicates time The temperature standard deviation at the moment measures the dispersion of the temperature of each node. Exceeding the set normal operating threshold When , an alarm signal is issued, marking the time period as abnormal: , then an alarm is issued, Indicates the maximum standard deviation allowed for temperature response under normal operating conditions.

[0178] Under dynamic load conditions, calculate the slope of the temperature under load conditions , evaluate the cable's ability to respond to load fluctuations:

[0179] ,in, Representation Node In time The rate of change of temperature at a moment, that is, the temperature response speed caused by load fluctuations, Represents the time interval used to calculate the temperature change rate, perform mean and standard deviation analysis on the temperature change rate of all nodes, and evaluate the performance of the cable under dynamic load: ,in, Indicates time The average temperature change rate of all nodes at the moment is used to evaluate the overall response speed of the cable.

[0180] ,in, Indicates time The standard deviation of the temperature change rate at each moment,

[0181] When the standard deviation Exceeding the set threshold When the alarm is sounded: , an alarm is sounded, Indicates the maximum standard deviation allowed for the temperature response change rate under dynamic load.

[0182] Detect the transient response time of each node , that is, the time required for the cable temperature to reach a certain set value after the impact occurs. The transient response time is calculated as:

[0183] ,in, Representation Node The transient response time, that is, the temperature first reaches The moment of time, Indicates the set temperature threshold, marking whether the cable successfully responds to the high voltage shock.

[0184] Calculate the mean and standard deviation of the transient response time of each node:

[0185] ,in, represents the average transient response time of all nodes,

[0186] ,in, Represents the standard deviation of transient response time, which measures the discreteness of each node’s response time.

[0187] when Exceeding the set threshold When an abnormal response alarm is issued: , an abnormal response alarm is issued. represents the maximum allowable standard deviation of the transient response time,

[0188] Perform a global analysis of the temperature response of each node, calculate the mean and standard deviation of the node under all working conditions, and summarize the temperature data under normal working conditions, dynamic loads, and high-pressure shock conditions:

[0189] ,in, represents the average temperature of all nodes in all time periods, Represents the total number of time periods, that is, the total time under all test conditions.

[0190] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A temperature sensing cable alarm testing method based on the Internet of Things, characterized in that: The following steps are included: Step S1, temperature sensing cable data collection, The temperature sensors deployed on the temperature-sensing cable nodes collect the node temperature data in real time and transmit the temperature data to the remote server using the NBIoT wireless network. Step S2, dynamic load test, The remote server performs dynamic load testing based on the temperature data in S1, simulating fluctuations and load changes in the power grid, adjusting voltage, current and frequency parameters while monitoring temperature changes under different load conditions, marking abnormal data and issuing alarms. Step S3, high voltage shock test, Based on the temperature data in S1, the remote server simulates sudden high voltage or lightning strike scenarios, performs high voltage impact tests, and tests the transient response capability of the cable. Step S4, response uniformity test, Based on the dynamic load test data and high-voltage impact data in S2 and S3, the transient false alarms and real fire signals are distinguished, the alarm responses at different locations are analyzed, and the response of the cable at different locations is tested to see whether it is uniform. When an abnormality is detected, a local alarm is issued. Step S5, comprehensive data analysis, Analyze the data output from step S1 to step S4, including normal working conditions, dynamic load, high voltage shock and multi-point response performance, compare the data under different conditions, and generate a test report; In step S2, the method of performing the dynamic load test also includes: To perform temperature over-limit detection: When the temperature Exceeding the set threshold When the alarm is triggered, To perform response hysteresis detection: Real-time monitoring of the slope of temperature change , detect whether the temperature responds too slowly after the load changes. If the temperature response lag time Exceeding critical value , it is marked as response lag and an alarm is issued: ,like , then an alarm is triggered, where is the upper temperature limit, is the maximum allowable lag time of the temperature response, At every point in time Based on the monitored temperature data , compared with the set threshold And the lag time of detecting temperature response , determine whether to trigger an abnormal alarm; In step S3, the high voltage shock test method is: Simulate sudden high voltage shock scenario: ,in, Indicates time The transient impulse voltage that the cable is subjected to at any moment, Indicates the steady-state voltage value, that is, the voltage value of the cable under normal operation. Indicates the ratio of high-voltage shock amplitude, that is, the intensity of transient shock. It represents the shock wave attenuation coefficient, controls the attenuation speed of transient shock, and simulates the natural decay process after voltage shock. Represents the angular frequency of the impact event, used to describe the high-frequency electromagnetic interference effect, represents the time variable, i.e. the time when the shock occurs, Simulate the transient change of current: ,in, Indicates time The instantaneous current value of the cable at the moment, Indicates the steady-state current value, that is, the current of the cable under normal operation. represents the phase shift of the current, Perform transient power calculations and thermal effect simulations: ,in, Indicates time The transient power value at the moment, that is, the power consumed by the cable when it is subjected to high voltage shock. and Represents the transient voltage and current respectively This power will cause the cable temperature to rise, and the temperature response can be expressed as: ,in, Indicates time The cable temperature at the time, Indicates the initial temperature or ambient temperature, that is, the temperature of the cable before the impact, Indicates the thermal resistance of the cable, that is, the ability of the cable to resist temperature changes. represents the instantaneous power, Indicates the thermal capacity of the cable, that is, the ability of the cable to store heat. Represents the thermal time constant, i.e., the temperature response speed; Perform transient response capability test and calculate the temperature change rate: ,in, Indicates the rate of change of temperature over time, compared to the rate of change of temperature and preset response thresholds , to determine whether the cable responds fast enough. If the temperature change rate is lower than the threshold, it means that the cable fails to respond to the sudden high-voltage shock in time, and an alarm is triggered. There are two types of abnormal conditions in cables during sudden high voltage shocks: Temperature Exceeds Limit: If the temperature Exceeding the preset safety threshold , then alarm, Response hysteresis: The hysteresis of the detection temperature change rate. If the response time Exceeding the set allowed time , then alarm, Indicates the response time of the cable from high voltage shock to significant temperature change. Indicates the maximum allowed response time.

2. According to the Internet of Things-based temperature-sensitive cable alarm testing method according to claim 1, it is characterized in that: The abnormal data marked in step S2 include temperature exceeding the limit and response hysteresis.

3. A temperature sensing cable alarm testing method based on the Internet of Things according to claim 2, characterized in that: In step S2, the dynamic load test is performed as follows: Construct a dynamic model of voltage, current, and frequency. Assume that the voltage at a certain moment is , the current is , the frequency is And they are all time functions, then their volatility is expressed as: ,in, It's time The voltage value at the moment, is the reference voltage, is the coefficient of voltage fluctuation amplitude, is the basic frequency of the power grid, electricity Flow and frequency The fluctuation expression of is: ， ,in, It's time The current value at the moment, is the reference current is the coefficient of the current fluctuation amplitude, is the phase difference of the current fluctuations, It's time The frequency value at the moment, is the standard frequency of the power grid, is the coefficient of the frequency fluctuation amplitude, temperature Will be affected by voltage , Current , and the frequency The power equation is used here to associate the parameters. It is expressed as: , temperature changes It is expressed by the heat conduction equation: ,in, It's time The temperature of the moment, is the initial temperature, is the thermal resistance of the cable, is the thermal capacity of the cable, is the thermal time constant.

4. The temperature sensing cable alarm testing method based on the Internet of Things according to claim 3 is characterized in that: In step S4, the response uniformity test method is: Analyzing the temperature signal in the frequency domain, the real fire signal is characterized by a continuous temperature rise with a low frequency, while the transient false alarm signal is a high-frequency short-term fluctuation. Here, Fourier transform FFT is used to convert the temperature signal from the time domain to the frequency domain for spectrum analysis: ,in, Indicates temperature signal Represented in the frequency domain, Indicates time The temperature signal at the moment, represents the frequency component, that is, the frequency of the signal, represents the imaginary unit, that is, the transformation of complex space, Analyze the spectrum obtained after Fourier transform , detect the frequency components of the signal. If there is an obvious energy peak in the high frequency band, it is judged as a transient false alarm. If the low frequency component gradually increases, it is judged as a real fire signal. False alarm judgment criteria: Setting frequency threshold , when the frequency If the energy If it is higher than the set value, it is considered as a transient false alarm. ,and It is considered a false alarm. represents the frequency domain energy threshold, True fire judgment criteria: On the contrary, if the signal energy is concentrated in the low frequency band , and the duration is long, it is defined as a real fire signal. ,and , it is regarded as a real fire signal. Indicates the low frequency energy threshold of the fire signal.

5. The temperature sensing cable alarm testing method based on the Internet of Things according to claim 4 is characterized in that: In step S4, the response uniformity test method further includes: The temperature response of multiple nodes is analyzed. Temperature sensors are arranged at different locations to record the temperature signal of each node ,in , calculate the deviation of each node from the mean temperature: ,in, Representation Node The deviation from the mean temperature, Representation Node The temperature, represents the average temperature of all nodes, Calculate the temperature standard deviation of all nodes. The larger the standard deviation, the more uneven the response: ,in, Indicates time The standard deviation of the temperature response at time, When the standard deviation Exceeds the set uniformity threshold When the cable is not responding uniformly, a local alarm is sounded: , a local alarm is issued, represents the uniformity threshold, i.e. the maximum allowed temperature response deviation, The temperature response of each node , set the allowed response range , when the node temperature When the range is exceeded, a local abnormal alarm is triggered: ,or , then a local abnormal alarm is triggered. and Indicates the preset upper and lower temperature limits. Combine the abnormal signals of multiple nodes to detect whether the nodes in a certain area are abnormal at the same time and issue a regional alarm. adjacent nodes, if more than If all nodes exceed the limit at the same time, a regional alarm will be issued: , a regional alert is issued. is the indicator function, when If true, the value is 1, otherwise it is 0. It is the node number threshold that triggers the regional alarm.

6. The temperature sensing cable alarm testing method based on the Internet of Things according to claim 5 is characterized in that: In step S5, the comprehensive data analysis method is: Normalize the data: ,in Representation Node In time The normalized temperature at time, Representation Node In time The original temperature data at the time, and Representation Node The temperature data of all nodes are normalized to the minimum and maximum temperature values ​​during the test. interval, Calculate the average temperature under normal operating conditions and standard deviation : ,in, Indicates time The mean temperature of all nodes at the moment, Represents the total number of nodes, ,in, Indicates time The temperature standard deviation at the moment measures the dispersion of the temperature of each node. Exceeding the set normal operating threshold When , an alarm signal is issued and the corresponding time period is marked as abnormal: , then an alarm is issued, Indicates the maximum standard deviation allowed for temperature response under normal operating conditions. Under dynamic load conditions, calculate the slope of the temperature under load conditions , evaluate the cable's ability to respond to load fluctuations: in, Representation Node In time The rate of change of temperature at a moment, that is, the temperature response speed caused by load fluctuations, Represents the time interval used to calculate the temperature change rate, perform mean and standard deviation analysis on the temperature change rate of all nodes, and evaluate the performance of the cable under dynamic load: ,in, Indicates time The average temperature change rate of all nodes at the moment is used to evaluate the overall response speed of the cable. in, Indicates time The standard deviation of the temperature change rate at each moment, When the standard deviation Exceeding the set threshold When the alarm is sounded: , an alarm is sounded, Indicates the maximum standard deviation allowed for the temperature response change rate under dynamic load. Detect the transient response time of each node , that is, the time required for the cable temperature to reach a certain set value after the impact occurs. The transient response time is calculated as: ,in, Representation Node The transient response time, that is, the temperature first reaches The moment of time, Indicates the set temperature threshold, marking whether the cable successfully responds to the high voltage shock. Calculate the mean and standard deviation of the transient response time of each node: ,in, represents the average transient response time of all nodes, ,in, Represents the standard deviation of transient response time, which measures the discreteness of each node’s response time. when Exceeding the set threshold When an abnormal response alarm is issued: , an abnormal response alarm is issued. represents the maximum allowable standard deviation of the transient response time, Perform a global analysis of the temperature response of each node, calculate the mean and standard deviation of the node under all working conditions, and summarize the temperature data under normal working conditions, dynamic loads, and high-pressure shock conditions: ,in, represents the average temperature of all nodes in all time periods, Represents the total number of time periods, that is, the total time under all test conditions.

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